Influence of silsesquioxane coatings on interfacial and impact properties of carbon fiber-polyarylacetylene composites

A carbon fiber surface is treated with silsesquioxane (SSO) coatings, including methyl-SSO (MES-SSO), vinyl-SSO (VMS-SSO), and 3-(methacryloxy) propyl-SSO (MPMS-SSO). The mechanical behavior of the carbon fiber-polyarylacetylene (CF-PAA) composites is studied in terms of force modulation mode atomic force microscope (AFM), short-beam bending, micro-debonding, and impact tests. A transitional layer appears between the fiber and resin after the carbon fibers are treated with SSO coating. Based on experimental results, The authors conclude that the mechanical interfacial properties of the composites, i.e., interlaminar shear strength (ILSS) and interfacial shear strength (IFSS), are largely increased by the SSO coatings on the fiber surface. Impact properties of the composites are also dominated by SSO coatings. These results could be explained as probably due to the effect of SSO coatings, resulting in improved ductile fracture properties, thereby increasing the resistance to deformation and crack initiation of the polyarylacetylene system.